Blancpain's Fifty Fathoms Tech BOC IV

The Blancpain Fifty Fathoms Tech BOC IV case

The 45 mm, grade 23 titanium case of the Fifty Fathoms Tech Dive BOC IV features a decompression valve at the 10 o'clock position, which is essential for saturation diving in a hyperbaric chamber. The unidirectional bezel features a domed black ceramic insert and is angled towards the dial for easy operation, even when wearing diving gloves. Blancpain describes the deep black dial as absorbing up to 97% of light, ensuring optimal readability underwater, thanks also to the applied, domed, luminescent hour markers. The central seconds hand is the same shade of blue as the 'Tech' lettering at the 6 o'clock position, enhancing aesthetic consistency.

Blancpain Fifty Fathoms 70th Anniversary Act 2 Tech Gombessa

The Fifty Fathoms 70th Anniversary Act 2 Tech Gombessa watch. Its aesthetics have inspired the newly presented watch. However, the differences between the two are as evident as the similarities. As well as the dimensions and bezel, which we wrote about in the article, note the orange hour markers and hands, as well as the orange 'Tech' lettering at 6 o'clock. This identifies the line as being aimed more specifically at professional divers. Not to mention the calibre: here, it is the 13P8, developed specifically for managing dive times on the 3-hour graduated scale. Unlike the Fifty Fathoms Tech BOC IV, the Gombessa is not a limited edition and is significantly more expensive at €31,000.

The Fifty Fathoms Tech BOC IV case houses the 1315 automatic calibre. This is one of Blancpain's most reliable automatic movements and powers many references in the Fifty Fathoms collection. It has a five-day power reserve. First introduced to the collection in 2007, this movement features an anti-magnetic silicon balance spring and operates at a frequency of 28,800 vibrations per hour. It uses a free-sprung Glucydur balance with gold adjustment screws. The 18-carat gold oscillating weight, decorated with the blue BOC logo, is visible through the sapphire case back. This is the signature of all watches created in support of the Blancpain Ocean Commitment.

This close-up shot reveals the two screws that secure the rubber strap directly to the watch case. Blancpain's designers developed central lugs to improve the watch's overall structure, making it more compact and robust while ensuring a comfortable fit. This means that the Fifty Fathoms Tech BOC IV can be worn either directly on the wrist or over a diving suit with ease and comfort.

the three previous models of the Fifty Fathoms BOC

Three previous references have been dedicated to the Blancpain Ocean Commitment programme. From left to right in the image above, the 2014 and 2016 editions were Fifty Fathoms Bathyscaphe watches with grey and blue ceramic cases, respectively. The 2018 edition was a Fifty Fathoms Automatic with the Blancpain Ocean Commitment logo at the 6 o'clock position.

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Blancpain is a strategic partner of the Professional Association of Diving Instructors' (PADI) Blueprint for Ocean Action and a founding partner of Adopt the Blue, as well as its dedicated platform. Blancpain's commitment to the oceans is certainly not static. In fact, it is constantly evolving in response to new environmental threats and collaborations. Throughout all this, however, one thing remains constant: Blancpain's determination to make a difference, both now and for future generations.

The island of Pangatalan, home to the Sulubaaï Environmental Foundation, whose projects are funded by proceeds from the Fifty Fathoms Tech BOC IV

Pangatalan Island is home to the Sulubaaï Environmental Foundation, established in 2012, which has been supported by Blancpain since 2020. The Palawan archipelago in the Philippines is a biodiversity hotspot, but it is under threat from overfishing and destructive underwater practices. The project to protect, conserve and restore natural resources involves local populations and consists of four steps: establishing a network of marine protected areas, restoring damaged coral reefs and repopulating them with fish, studying the reef and fish fauna, and raising awareness through school involvement in resource management.

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18 March 2025

Written by Davide Passoni

This post is also available in: Italian

Blancpain occasionally updates its Fifty Fathoms collection to support environmental causes. This is when things get really serious. Proof of this is the recently unveiled Fifty Fathoms Tech BOC IV. For those unfamiliar with the brand, Blancpain is committed to setting a good example. In other words: I produce exquisite diving watches for professional divers. This means ensuring that the environment in which they dive, whether for pleasure or work, remains as intact as possible. How do I do this? By allocating part of the proceeds from the sales of my diving watches to fund ocean and marine environment protection projects.

A love for the oceans

A strategy with a name: Blancpain Ocean Commitment. It pays tribute to Blancpain’s long-standing relationship with the ocean, which began in 1953 with the launch of the Fifty Fathoms — the world’s first true diving watch. This marked the beginning of the brand’s support for ocean exploration and its numerous collaborative initiatives with local communities to conserve biodiversity.

Specifically, the Fifty Fathoms Tech BOC IV supports the Blancpain x Sulubaaï Marine Research Centre, which is an extension of the Sea Academy programme launched on 7 February. Since 2020, Blancpain has supported this programme, run by the Sulubaaï Environmental Foundation, which promotes the sustainable management of marine resources through collaboration. It focuses on establishing a network of marine protected areas in partnership with local communities around Pangatalan Island and Shark Fin Bay in Palawan, Philippines.

The initiative requires funding to remain operational ‒ specifically, €100,000. Therefore, Blancpain will donate €1,000 for each of the 100 watches in the limited-edition Fifty Fathoms Tech BOC IV collection. For reference, the watch costs €23,450.

A few words about the Fifty Fathoms Tech BOC IV

What makes this watch so special? Aesthetically, it is reminiscent of the 2023 Fifty Fathoms Tech Gombessa. However, the latter had a 47 mm case and a special graduated bezel with a diving scale up to three hours; the former has a 45 mm case and a classic 60-minute bezel.

The watch case is made of titanium. The combination of the metal case and rubber strap creates a sense of lightness. I wore this Fifty Fathoms during the presentation to the Italian press, so I can vouch for that. Absence of lugs and special strap attachment to the side of the case ensure an optimal fit. The fact that it fits my slim wrist perfectly speaks for itself.

The overall aesthetic is that of the Fifty Fathoms collection, and there are a few details worth mentioning before letting the captions speak for themselves. These include the classic domed bezel with a ceramic insert and the deep black dial with applied hour markers filled with Super-LumiNova. The ergonomics make the Fifty Fathoms Tech BOC IV a professional watch above all else. Then, if anything, it is an ornament.

The Fifty Fathoms collection and the environment

As I mentioned, only 100 of these watches will be produced. For each one sold, Blancpain will donate €1,000 to the Sulubaaï Environmental Foundation. As the name of the watch suggests, this is the fourth edition dedicated to developing projects under Blancpain’s environmental programme to protect the marine environment (BOC stands for Blancpain Ocean Commitment).

The previous three limited editions were launched in 2014, 2016, and 2018. Blancpain produced 250 pieces for each edition, contributing €1,000 per watch to an equal number of environmental protection projects. The operations supported by the first three editions were more complex and required €250,000 each. The Fifty Fathoms watches dedicated to this cause sold out quickly.

Blancpain emphasises that it does not randomly select the projects it supports. They must meet specific requirements that align with the company’s aims and values. Blancpain’s President and CEO, Marc Hayek, plays a personal role in selecting worthy initiatives, driven by his strong environmental awareness and passion for diving. The company provides high-quality watches, the price of which is secondary to the “mission” of each one (for those who can afford them…). I commend the team effort and ‘partnership’ between the Maison, environmental organisations and passionate collectors.

Blancpain is not the only watchmaker to produce diving watches and support environmental initiatives to protect the seas. What sets Blancpain apart is not only the diving performance, but also the direct involvement of top management in all processes related to these initiatives. When the boss is involved, you can be sure that the result will be excellent in terms of both the product and the project as a whole.